With the arrival of increasingly complex engines, which state at high revolutions per minute (RPM) and need all their power to idle, it is necessary to be able to advance the opening and closing times of the intake and exhaust valves precisely at any engine speed. For this reason, variable valve timing was created-

It is a system that aims to alter the opening and closing time of the air intake valves (or exhaust gases) so that the optimum amount of air for the process enters the cylinders. This is possible by a phaser located on the camshaft head called Variable Valve Timing (VVT) System.

Keep reading to find out in more detail how this system works and what it is made of.



Variable Valve Timing: Purpose and operation


As a rule, when more revolutions our engine has, more air is needed by cylinders. That’s where variable valve timing comes in. Its main function is to modify the phase angles of the distribution diagram, adjusting the camshaft according to the needs of the moment.

This VVT system is controlled by the ECU, the electronic control unit that regulates the engine and is responsible for activating this gear through the flow of engine oil.

Oil pressure is sent through the VVT gear to fill up cavities to advance or retard timing. Filling the VVT ​​gear with oil unlocks its stationary pin and makes it two independent rotating parts, causing angular displacement between the input (chain) and output (camshaft), advancing, or retarding the timing.


Keep reading: The different timing chain systems


To obtain the maximum efficiency of the engine, the valves must open and close depending on the revolutions per minute at which it is turning, and this is only possible if we have a variable timing.

There are different types of timing that have unique characteristics, the main difference being in the placement of the camshaft. Depending on the engine, VVT configurations are differentiated and can be run only on the intake valves or on both camshafts.

The two main ones, when it comes to varying the distribution, are:

  1. Variation of the valve lift, varying the advance and closure of the valve at the same time.
  2. Displacement of the camshaft with respect to the crankshaft.



Advantages of Variable Valve Timing (VVT)


Chain drives can transmit large loads on long and short distances. These systems allow to use the optimal opening and closing time of the valves in any engine situation. Therefore, the importance of the VVT lies in the fact that its proper use directly improves the performance of our vehicle’s engine, optimizes thermal management, and provides a better fuel economy.

The main benefits of this system include:

  • Improved efficiency, increased torque, and power: The variable valve timing system allows higher RPM to be achieved, and consequently greater engine power.
  • More precise engine timing: It allows minute and precise control of the internal valves (opening and closing) of the engine while driving, therefore it will also obtain an increased engine lifespan.


  • Reduction of fuel consumption: Thanks to this effective management of the engine valves, the VVT allows a smoother idle offering better fuel consumption as well as lower carbon emissions.
  • Better fuel economy: By having a greater direction and control of the gases, the system performs a recirculation that can reduce emissions.



Variable Valve Timing System: Main components


The main elements of a variable valve timing that come into action to obtain a variable synchronization are:

  • ECU (Engine Control Unit)
  • Sensors
  • VVT Camshaft adjuster consisting of stator, rotor, vanes and locking element
  • Camshafts
  • Solenoid valves
  • Oil

Because of the importance of lubrication throughout the variable valve timing system, monitoring oil levels and condition will be essential to keeping all parts in top condition and getting the best possible engine performance. This action must be carried out in accordance with the vehicle manufacturer’s recommendations.



VVL / VVEL / VVTL: Main differences


VVL, VVEL, and VVTL are all abbreviations for technologies that involve altering the lift of engine valves for improved performance. VVL stands for “Variable Valve Lift”, VVEL stands for “Variable Valve Event and Lift”, and VVTL stands for “Variable Valve Timing and Lift.”

In particular, VVTL is an advanced supporting system that allows for precise control of valve lift. In modern engines, the VVL system is often combined with Variable Valve Timing (VVT) systems to achieve even greater performance improvements.

Moreover, various manufacturers utilize proprietary abbreviations for their Variable Valve Timing (VVT) systems, including:

SL. Acronym

Full Form



Continuous Variable Valve Timing



Continuous Variable Valve Timing



Variable Cam Timing



Variable Valve Timing



Variable Valve Timing



Dual Continuous Variable Cam Phasing


7 VVTi

Variable Valve Timing (intelligent)



Variable Timing and Valve Train



Nissan-Variable Cam Timing


10 S-VT

Sequential Valve Timing



Mitsubishi Innovative Valve timing Electronic Control


12 i-VTEC

Intelligent – Variable Valve Timing and Lift Electronic Control

Honda, Acura

13 Camtronic

Mercedes Benz


Variable Nockenwellensteuerung


15 Valvelift


16 VarioCam



Related content: Timing chain system: Frequently Asked Questions


Dolz: Solutions in Timing Chain Kits


Thanks to its almost 90 years of experience in the automotive aftermarket industry, Industrias Dolz offers the most competitive timing chain kits on the market, providing its customers with the best solutions with excellent quality, service, and innovation.

The manufacturing processes used in the kits and their different components only use selected materials, ensuring that all products always remain at the forefront of the market and stand out as the ‘top sales’ range among the European market offers.


Chain kit box


Also, they include all the necessary components for a professional repair, that is all components are delivered in one package: timing chain, crank sprocket, cam sprocket, tensioner, guides, oil seal, VVT… all the necessary accessories depending on the vehicle application.




Don’t miss… Dolz Timing Chain Kit Unboxing Video


The main characteristics of our Timing Chain Kits are:

  • All our components have been tested and are equivalent to OE.
  • Always with the latest OE version, to guarantee an effective replacement and an efficient and durable chain drive.
  • Easy-Fit Kits for a correct installation.
  • Technical Bulletin if necessary.
  • All our components are marked with our brand.
  • A careful and innovative high-quality packaging
  • Presence in TecAlliance electronic catalog (TecDoc).
  • 2-year warranty from the date of purchase or 80,000 km.

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